The present invention relates generally to nozzle configurations for air jet looms and, more particularly, to a nozzle for holding fill yarns in place where multiple parallel fill yarns form each weave pattern.
Air jet looms have been in use in the textile industry for a number of years. In operation, these shuttleless looms form woven fabric in much the same manner as other looms, except that one or more air jets are used to propel the fill yarns across the shed. These looms-also typically employ several auxiliary air nozzles that are spaced apart in the shed of the warp yarns to aid in transporting a fill yarn along a straight path to the opposite side of the loom. In operation, an air jet propels the leading end of the fill yarn with a directed stream of air. Once the fill yarn reaches the other side, it is detected by a feeler head, or electronic eye. The reed of the loom then beats the fill yarn up against the fell line. The loom""s two harnesses, that are conventional in any type of loom, cross one another, closing, and then opening a new shed, and thus locking the fill yarn into the woven fabric. Few problems arise with this woven construction which uses only a single fill yarn between each reciprocation of the harnesses, and the woven fabric is very uniformly formed. Unfortunately, this is not the case with yarn constructions in which two or more fill yarns are introduced between harness reciprocations, sometimes referred to as xe2x80x9cbasket weavexe2x80x9d patterns.
Basket weave patterns are formed in a somewhat different fashion. A first fill yarn is propelled through the shed and beaten up against the fell line by the reed that moves forward with each fill cycle. As the reed pivots rearwardly away from the fell line, the harnesses do not cross as in the single fill weave construction. Rather, at least one additional fill yarn is propelled through the same open shed to complete the 2xc3x972, 3xc3x973, etc. pattern. Since the harnesses do not cross until the entire set of parallel fill yarns have been propelled across the loom, the fill yarns tend to be pulled back with the reed as the reed moves rearwardly away from the fell line. The extent to which this occurs is dependent on the number of fill yarns and type of yarn being woven. Sized synthetic yarns such as polyester and nylon have xe2x80x9cslickerxe2x80x9d surfaces that are more susceptible to this phenomenon, particularly where they have flat geometries. Because of this pull-back, the second fill yarn frequently crosses over the first, creating a loop, or rollover, of the two fill yarns. This results in a defect in the form of a woven fabric that has a non-uniform woven structure, an unacceptable appearance where the fill yarns of different colors are used in the weave, and does not meet a customer""s quality standards. Simply, the woven fabric is not marketable and cannot be sold.
It is known in the art to place auxiliary nozzles along the length of the sley shaft in front of the reed to aid in transporting the fill yarn in a straight path to the opposite side of the loom. The nozzles, sometimes referred to as xe2x80x9cshower headxe2x80x9d nozzles, however, are directed parallel to the path of the fill yarn, but provide no assistance in holding fill yarns firmly against the fell line.
The present invention is directed to the use of one or more xe2x80x9cholding nozzlesxe2x80x9d for fill yarns in an air jet loom that operate synchronously with the introduction of the fill yarns to address the problems described above. As used herein, a xe2x80x9cholding nozzlexe2x80x9d is an air nozzle placed in the shed of the loom and directed perpendicularly toward the previously deposited fill yarn. The holding nozzle(s) hold parallel fill yarns of a pattern set in position against the fell line on an air jet loom so that xe2x80x9cloopsxe2x80x9d, or xe2x80x9crolloversxe2x80x9d, between individual fill yarns will not occur, distorting the fabric and rendering it commercially worthless. As used herein a xe2x80x9cpattern setxe2x80x9d refers to the total number of yarns that comprise each pattern; e.g., a total of 2 in a 2xc3x972 pattern. One or more of the nozzles may be installed on any air jet loom of the type having a sley shaft or other pivotal axle, a reed, and at least one air jet for propelling fill yarns through the shed formed by the harnesses of the loom.
In a preferred embodiment, one or more holding nozzles are mounted on the sley shaft, or at any other workable position within the shed of the loom. Each holding nozzle includes a tube mounted in or on a holder. The shape and size of the tube holder is not a critical aspect of the construction of the holding nozzle; the tube holder serves only as a mounting platform for the tube. A tube having an air intake end, a closed end, and an aperture formed at a selected point along the length of the tube, is secured in the holder. While the tube is desirably a single piece for ease of fabrication, it may be comprised of multiple pieces so long as it performs the intended function described herein. While a xe2x80x9ctubexe2x80x9d normally refers to a cylindrical, hollow member, the term as used herein refers to other shapes as well. For example, many conventional tubes, as that term is used in the textile art, have cross-sections that are oval or have flat sides and rounded ends, such as shower head tubes. Shape is critical; the important aspect is that these hollow members have geometries and an aperture located to direct a stream of air at a selected position on the fell line.
When each holding nozzle is properly positioned, the aperture directs a jet of air transversely against the previous fill yarn, and perpendicular to the fell line. After each of the air jets fires a fill yarn, the aperture discharges air against the fell line to hold the fill yarn in place until the reed beats up against the fell line and the loom""s harnesses cross to lock in the weave pattern.
In the operation of forming a 2xc3x972 basket weave pattern, for example, the weave construction begins by a first air jet firing a first fill yarn across the front of the reed through the open shed formed by the harnesses. The sley shaft of the loom then rotates, pivoting the reed to the fell line of the woven fabric where the fill yarn is beaten-up, or packed, against the edge of the fabric just formed. Certain yarn materials, such as multi-filament polyesters and nylons, tend to be xe2x80x9cslickxe2x80x9d, and thus slide easily over like yarns. Thus in a basket or other similar weave pattern in which the previous fill yarn is not locked in place, there is a tendency for the first fill yarn to xe2x80x9cpull-backxe2x80x9d from the fell line with the reed, when the reed retreats rearwardly, for the next fill cycle in the weaving process.
After the first fill yarn is fired and detected on the opposite side of the loom (by sensors or electronic eyes known in the art), the reed beats up against the fell line and then pivots rearward. At a predetermined time during the rearward movement of the reed, the holding nozzles of the present invention begin discharging air to hold the first yarn in place against the fell line. The nozzle discharge continues until the subsequent fill yarns in the fill pattern have been fired and beaten up by the reed. Thus, in a 2xc3x972 weave, the nozzles will begin blowing with the retreat of the reed following beatup of the first fill yarn and continue to direct air toward the fell line until beating up of the second fill yarn is complete and the harnesses have crossed, locking the fill yarns in place in the woven fabric.
The number of holding nozzles installed within the shed is dependent upon the length of the reed, the type of yarn selected for the application, and the placement of other auxiliary nozzles within the shed. In the Picanol loom described herein, a minimum of 3 nozzles interspaced between the auxiliary nozzles was found to be adequate for the holding function along the length of the fell line.
These and other aspects of the present invention will become apparent to those skilled in the art after a reading of the following description of the preferred embodiment when considered with the drawings.